Just 23 years old, Holloman received a second opinion from a doctor who recommended he immediately retire. He will reportedly seek out a third opinion.

"I don't want to get into anything medical about it," Cowboys head coach Jason Garrett said. "I don't know that much about it, and there's a lot of very specific things regarding that. But it has to do with his neck and he had that injury last year and he dealt with it again this year."

It's a very challenging, difficult thing for a young man who has dreams of being an NFL football player, achieves those dreams," he added.

In what could be his final NFL game, Holloman recorded 11 tackles and two sacks in Week 17 against the Philadelphia Eagles.

Holloman was selected in the sixth-round of the 2013 Draft. He made 26 tackles in nine games during his potentially lone season in the NFL.